The lithium halide battery has become relatively well known to those skilled in the art, U.S. Pat. No. 3,660,163. These batteries have also been accepted for use in cardiac pacers and other types of implantable devices, see generally U.S. Pat. Nos. 3,723,183, 3,895,962, 3,874,929, 3,981,744, 4,010,043 and 4,072,803. Each of the aforementioned patents describes a lithium halide battery adapted for use in cardiac pacers.
Typically, the depolarizer comprises a charge transfer complex and a halogen such as iodide. A problem that exists in designing such batteries is the prevention of iodine leakage. Charge transfer complex migration can cause internal short circuiting of the battery or, if iodine flows externally of the cell, the cardiac pacer can be destroyed. In U.S. Pat. No. 3,874,929, for example, a lithium iodide battery is disclosed in which the anode current collector is positioned between a pair of lithium anode members and is connected to an anode conductor. Leakage is prevented by a ferrule extending the length of the conductor to shield it from the cathode or depolarizer material. The protective ferrule includes a halar sheathing about the conductor; a second layer of halar around the sheath; and an outer metal portion enveloping the second layer.
Another method of avoiding leakage is disclosed in U.S. Pat. No. 4,072,802 wherein the cathode and anode leads are embedded within the side walls of an anode depolarizer container. U.S. Pat. No. 3,981,744 shows yet another method utilizing inverted casings and a hermetically sealed outer metal container.
Each of the described devices have purported advantages. However, each of the known batteries is costly to assemble because of design complexities. Accordingly, it is an object of the present invention to provide a battery having a lower inherent cost because of greater design simplicity and fewer parts. It is a further advantage of the invention to provide a battery having a high relative energy density and improved current capacity. Additionally, it is an object of the invention to provide a battery having smaller physical dimensions as well as a smaller cardiac pulse generation without loss of operating life.